The application relates to polyester carbonate and more particularly to a melt transesterification process for its manufacture.
A transesterification process for producing polyester is disclosed. In a first stage of the process there is heated, in an inert gas atmosphere, a first mixture containing at least one dihydroxy compound and at least one diaryl carbonate to form an oligocondensate. In a second stage there is added to the oligocondensate at least one dicarboxylic acid to form a second mixture. The second mixture is heated to a temperature not higher than 290xc2x0 C. in the presence of a quaternary onium compound as catalyst to form polyester carbonate. Hydroxyaryl formed throughout the process is distilled-off under reduced pressure.
The production of polyester carbonates from difunctional, aliphatic carboxylic acids and dihydroxy compounds via the interfacial process is described for example in EP-A 433 716, U.S. Pat. No. 4,983,706 and U.S. Pat. No. 5,274,068. As is disclosed in EP-A 433 716, the known carboxylic acids for producing polyester carbonates can however be incorporated in significant amounts only by a complicated and expensive procedure in the interfacial process.
The incorporation of aromatic or aliphatic dicarboxylic acids via the so-called pyridine process is described in U.S. Pat. No. 3,169,121.
The transesterification process is well known for the incorporation of aromatic dicarboxylic acids and is described for example in U.S. Pat. No. 4,459,384. The incorporation of aliphatic dicarboxylic acids is described in JP-A 2000 248 057 although here, as is generally the case, all monomers are added jointly at the start of the reaction and are heated and/or condensed in common.
JP-A 3 203 926 likewise describes a transesterification process for the incorporation of aliphatic dicarboxylic acids. The dicarboxylic acids are in this case reacted with aromatic dihydroxy compounds and dicarbonates, alkali metal or alkaline earth metal compounds being used as catalyst. Apart from the proportion of incorporated dicarboxylic acid, no further details are given concerning possible secondary reactions or the intrinsic color of the polymers that are obtained.
Polyester carbonates that are produced by the interfacial process have a good intrinsic color, but contain minor amounts of anhydrides of the employed dicarboxylic acids or even free acid, which is undesirable. This is described in EP-A 926 177. However, in principle the object is to incorporate the dicarboxylic acids as completely as possible into the polyester carbonate so that as many ester bonds as possible in addition to as few acidic or anhydride structures as possible are present in the product, since these impair the stability of the polyester carbonate.
In contrast to this, although polyester carbonates that have been synthesised by the transesterification process contain few anhydride structures, nevertheless they normally have a strong intrinsic coloration, which in turn has to be as low as possible for most applications.
The object therefore existed of producing a polyester carbonate that on the one hand contains as many ester bonds as possible in addition to as few acidic or anhydride structures as possible, but that nevertheless on the other hand has a good intrinsic color.
This object was surprisingly achieved by the transesterification process according to the invention.
The present application accordingly provides a process for the production of polyester carbonates by transesterification of diaryl carbonates with dihydroxy compounds and dicarboxylic acids, characterised in that the condensation is carried out in the presence of quaternary onium compounds as catalysts, wherein the dicarboxylic acids are added only after the oligocondensation of the dihydroxy compounds and the temperature does not exceed 290xc2x0 C.
Furthermore, the present application also provides the polyester carbonates per se that can be obtained by the process according to the invention.
According to the process of the invention, in a first stage a mixture of dihydroxy compound and diaryl carbonate is heated in an inert gas atmosphere and under reduced pressure for 30 to 300 minutes, preferably for 60 to 150 minutes, up to a temperature of 200 to 290xc2x0 C., preferably 230 to 290xc2x0 C., particularly preferably 250xc2x0 to 280xc2x0 C., and the hydroxyaryl component that is formed is distilled off. The dicarboxylic acid or dicarboxylic acid mixture is then added in a second stage and the reaction mixture is heated for between 60 and 200 minutes, preferably between 90 and 180 minutes, at a temperature of not higher than 290xc2x0 C., and condensed to form the polyester carbonate. In each stage the pressure is chosen so that the hydroxyaryl component can be distilled off without any problem.
The polyester carbonate obtained according to the invention is light in color, i.e. it has a color number of  less than 0.2, and contains particularly low amounts of free dicarboxylic acid or anhydride structures and therefore satisfies the formula   Q  =                    x        +                              [                          10              ⁢                              (                                                      5                    ⁢                    y                                    +                                      4                    ⁢                    z                                                  )                                      ]                    2                    x         less than     1.3  
where
Q: is a characteristic number
x: is the wt. % of the esterified acid in the polyester carbonate
y: is the wt. % of free COOH in the polyester carbonate
z: is the amount, in wt. % of anhydride structural units in the polyester carbonate
Suitable dicarboxylic acids for the process according to the invention are those of the formula (I)
HOOCxe2x80x94Txe2x80x94COOHxe2x80x83xe2x80x83(I)
where
T denotes a branched or linear, saturated or unsaturated alkyl, arylalkyl or cycloalkyl radical with 8 to 40 carbon atoms.
Saturated linear alkyl diacids with 8 to 40 carbon atoms are preferred, diacids with 12 to 36 carbon atoms being particularly preferred. Of these classes of substances fatty acids, particularly preferably hydrogenated dimeric fatty acids, are particularly suitable.
Examples of dicarboxylic acids of the formula (I) or mixtures of such fatty acids are:
sebacic acid,
dodecanedioic acid,
stearic acid,
palmitic acid,
hydrogenated dimeric fatty acid, such as for example Pripol 1009 from Uniqema.
Pripol 1009 from Uniqema is a mixture of hydrogenated dimeric fatty acids that according to details given by Uniqema has roughly the following composition:
Particularly preferred are dodecanedioic acid and Pripol 1009.
Most particularly preferred is Pripol 1009.
Both a dicarboxylic acid of the formula (I) as well as a plurality of dicarboxylic acids of the formula (I) may be used.
The employed dicarboxylic acids as well as also the other raw materials that are used should of course be as pure as possible. In the case of commercial products the purity often varies greatly however. In particular fatty acids or hydrogenated dimerised fatty acids may contain considerable amounts of byproducts that are formed in their production.
The dicarboxylic acids and dihydroxy compounds may be used in the process according to the invention in a molar ratio X:1 therebetween, where 0 less than X less than 10, preferably 0.01 less than X less than 1, particularly preferably 0.02 less than X less than 0.5 and most particularly preferably 0.08 less than X less than 0.2.
The general or preferred definitions of radicals, parameters and/or explanations given above or hereinafter may also be arbitrarily combined with one another, i.e. between the respective ranges and preferred ranges. The details apply as appropriate to the end products as well as to the precursors and intermediate products and for processes as well as process stages.
Suitable dihydroxy compounds for the process according to the invention are those of the formula (II)
HOxe2x80x94Arxe2x80x94OHxe2x80x83xe2x80x83(II)
in which Ar is an aromatic radical with 6 to 30 C atoms, preferably with 6 to 25 C atoms, that may contain one or more aromatic nuclei, may be substituted, and may contain aliphatic or cycloaliphatic radicals or alkylaryl radicals or heteroatoms as bridge members.
Example of dihydroxy compounds of the formula (II) are:
hydroquinone,
resorcinol,
dihydroxydiphenyls,
bis-(hydroxyphenyl)-alkanes,
bis-(hydroxyphenyl)-cycloalkanes,
bis-(hydroxyphenyl)-sulfides,
bis-(hydroxyphenyl)-ethers,
bis-(hydroxyphenyl)-ketones,
bis-(hydroxyphenyl)-sulfones,
bis-(hydroxyphenyl)-sulfoxides,
xcex1,xcex1xe2x80x2-bis-(hydroxyphenyl)-diisopropylbenzenes as well as their nuclear-alkylated and nuclear-halogenated compounds.
These and further suitable other diphenols are described for example in U.S. Pat. Nos. 3,028,365, 3,148,172, 3,275,601, 2,991,273, 3,271,367, 3,062,781, 2,970,131 and 2,999,846, in DE-A 1 570 703, 2 063 050, 2 063 052, 2 211 0956, FR-B 1 561 518 and in the monograph xe2x80x9cH. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964xe2x80x9d.
Preferred dihydroxy compounds are for example:
4,4xe2x80x2-dihydroxydiphenyl,
2,2-bis-(4-hydroxyphenyl)-propane,
2,4-bis-(4-hydroxyphenyl)-2-methylbutane,
1,1-bis-(4-hydroxyphenyl)cyclohexane,
1,1-bis-(4-hydroxyphenyl)-4-methylcyclohexane,
xcex1,xcex1xe2x80x2-bis-(4-hydroxyphenyl)-p-diisopropylbenzene,
xcex1,xcex1xe2x80x2-bis-(4-hydroxyphenyl)-m-diisopropylbenzene,
bis-(4-hydroxyphenyl)-sulfone,
bis-(4-hydroxyphenyl)-methane,
1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,
bis-(2,6-dimethyl-4-hydroxyphenyl)propane,
bis-(4-hydroxyphenyl)hexafluoropropane,
(4-hydroxyphenyl)-1-phenylethane,
(4-hydroxyphenyl)diphenylmethane,
dihydroxydiphenylether,
4,4xe2x80x2-thiobisphenol,
bis-(4-hydroxyphenyl)-1-(1-naphthyl)ethane,
bis-(4-hydroxyphenyl)-1-(2-naphthyl)ethane,
dihydroxy-3-(4-hydroxyphenyl)-1,1,3-trimethyl-1H-inden-5-ol,
dihydroxy-1-(4-hydroxyphenyl)-1,1,3-trimethyl-1H-inden-5-ol,
2,2xe2x80x2,3,3xe2x80x2-tetrahydro-3,3,3xe2x80x2,3xe2x80x2-tetramethyl-1,1xe2x80x2-spirobi[1H-indene]-5,5xe2x80x2-diol.
Particularly preferred are:
resorcinol,
bis-(4-hydroxyphenyl)-1-(1-naphthyl)ethane,
bis-(4-hydroxyphenyl)-1-(2-naphthyl)ethane,
2,2-bis-(4-hydroxyphenyl)-propane,
xcex1,xcex1xe2x80x2-bis-(4-hydroxyphenyl)-p-diisopropylbenzene,
xcex1,xcex1xe2x80x2-bis-(4-hydroxyphenyl)-m-diisopropylbenzene,
1,1-bis-(4-hydroxyphenyl)cyclohexane,
bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,
bis-(4-hydroxyphenyl)diphenylmethane.
Most particularly preferred are:
bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,
4,4xe2x80x2-dihydroxydiphenyl,
2,2-bis-(4-hydroxyphenyl)propane.
Most preferred of all is bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane.
Both a diphenol of the formula (II) as well as a plurality of diphenols of the formula (II) may be used.
Diaryl carbonates within the context of the present invention are those carbonic acid diesters of the formula (III) 
wherein R, Rxe2x80x2 and Rxe2x80x3 may denote independently of one another H, optionally branched C1-C34 alkyl/cycloalkyl, C7-C34 alkylaryl or C6-C34 aryl, for example
diphenyl carbonate,
butylphenyl-phenyl carbonate, di-butylphenyl carbonate,
isobutylphenyl-phenyl carbonate, di-isobutylphenyl carbonate,
tert.-butylphenyl-phenyl carbonate, di-tert.-butylphenyl carbonate,
n-pentylphenyl-phenyl carbonate, di-(n-pentylphenyl) carbonate,
n-hexylphenyl-phenyl carbonate, di-(n-hexylphenyl) carbonate,
cyclohexylphenyl-phenyl carbonate, di-cyclohexylphenyl carbonate,
phenylphenol-phenyl carbonate, di-phenylphenol carbonate,
isooctylphenyl-phenyl carbonate, di-isooctylphenyl carbonate,
n-nonylphenyl-phenyl carbonate, di-(n-nonylphenyl) carbonate,
cumylphenyl-phenyl carbonate, di-cumylphenyl carbonate,
naphthylphenyl-phenyl carbonate, di-naphthylphenyl carbonate,
di-tert.-butylphenyl-phenyl carbonate, di-(di-tert.-butylphenyl) carbonate,
dicumylphenyl-phenyl carbonate, di-(dicumylphenyl) carbonate,
4-phenoxyphenyl-phenyl carbonate, di-(4-phenoxyphenyl) carbonate,
3-pentadecylphenyl-phenyl carbonate, di-(3-pentadecylphenyl) carbonate,
tritylphenyl-phenyl carbonate, di-tritylphenyl carbonate,
preferably
diphenyl carbonate,
tert.-butylphenyl-phenyl carbonate, di-tert.-butylphenyl carbonate,
phenylphenol-phenyl carbonate, di-phenylphenol carbonate,
cumylphenyl-phenyl carbonate, di-cumylphenyl carbonate,
particularly preferably diphenyl carbonate.
Furthermore, the phenolic compounds used as carbonates may also be used directly as hydroxyaryl compounds in addition to one of the aforementioned carbonates, in order to influence the terminal group of the polyester carbonates. Preferred mixtures are those containing diphenyl carbonate. According to the process of the invention it is possible to add the hydroxyaryl compound or the hydroxyaryl-containing compound at any time to the reaction mixture, preferably at the start of the reaction, and to split the addition into several portions. The proportion of free hydroxyaryl may be 0.4 to 17 mole %, preferably 1.3 to 8.6 mole % (referred to the dihydroxy compound). In this connection the addition may take place both before the reaction as well as wholly or partially during the reaction.
The carbonic acid diesters are used in a ratio of 1:0.9 to 1:1.3, preferably 1:1.0 to 1:1.2, particularly preferably 1:1.0 to 1:1.1, referred to the total of dihydroxy compound and dicarboxylic acid. Mixtures of the aforementioned carbonic acid diesters or dicarboxylic acids may also be used.
Ammonium compounds or phosphonium compounds may be used as catalysts for the synthesis, and are preferably used in amounts of 0.0001 to 0.5 mole %, referred to the total of dicarboxylic acid and dihydroxy compound, particularly preferably in amounts of 0.001 to 0.2 mole %.
Phosphonium salts, optionally in combination with other suitable catalysts that do not lead to a more intense intrinsic color, are preferably used as catalyst for the production of the polyester carbonates according to the invention.
Phosphonium salts within the context of the present invention are those of the formula (V) 
wherein R1-4 may denote the same or different C1-C10 alkyl, C6-C10 aryl, C7-C10 aralkyl or C5-C6 cycloalkyl radicals, preferably methyl or C6-C14 aryl radicals, particularly preferably methyl or phenyl, and Xxe2x88x92 may be an anion such as hydroxide, sulfate, hydrogen sulfate, hydrogen carbonate, carbonate, a halide, preferably chloride, or an alcoholate of the formula OR in which R may be C6-C14 aryl or C7-C12 aralkyl, preferably phenyl.
Preferred catalysts are
tetraphenylphosphonium chloride,
tetraphenylphosphonium hydroxide,
tetraphenylphosphonium phenolate,
particularly preferably tetraphenylphosphonium phenolate.
The polyester carbonates may be intentionally branched and may therefore contain minor amounts of 0.02 to 3.6 mole % (referred to the total of dicarboxylic acid and dihydroxy compound) of branching agents. Appropriate branching agents are those compounds suitable for the polycarbonate production and containing three or more functional groups, preferably those with three or more than three phenolic OH groups, for example 1,1,1,-tri(4-hydroxyphenyl)ethane and isatin biscresol.
In order to change the properties auxiliary substances and reinforcing agents may be added to the polyester carbonates according to the invention. Such known substances and agents include, inter alia, thermostabilizers and UV stabilizers, flow auxiliaries, mold release agents, flameproofing agents, pigments, finely divided minerals, fibrous substances, e.g. alkyl and aryl phosphites, phosphates, phosphanes, low molecular weight carboxylic acid esters, halogen compounds, salts, chalk, quartz flour, glass fibers and carbon fibers, pigments and combinations thereof. Such compounds are described for example in WO 99/55772 pp. 15-25, and in xe2x80x9cPlastics Additivesxe2x80x9d, R. Gxc3xa4chter and H. Mxc3xcller, Hanser Publishers 1983.
In addition other polymers may also be added to the polyester carbonates according to the invention, for example polyolefins, polyurethanes, polyesters, acrylonitrile/butadiene/styrene, and polystyrene.
These substances are preferably added to the ready-for-use polyester carbonate in conventional equipment, but depending on requirements may however also be added at another stage of the production process.
The polyester carbonates obtainable by the process according to the invention may be processed in the usual way in conventional machinery, for example in extruders or injection molding machines, into arbitrary molded articles, for example into films or sheets.
In addition to the use of the polyester carbonates and/or the corresponding molding compositions according to the invention for the production of molded parts and extrudates, the present invention also provides in particular optical articles, sheets and films and/or the corresponding molded parts, preferably optical articles, produced from the polyester carbonates according to the invention.
Examples of this use, which however should not be regarded as limiting, include:
1. Safety/security panels that, as is known, are required in many areas of buildings, vehicles and aircraft, as well as shields for helmets.
2. Production of extrusion sheets and solution sheets for displays or electrical motors, as well as sheet material for skis.
3. Production of transparent panels, in particular hollow chamber panels, for example for covering buildings such as stations, greenhouses and lighting installations.
4. For the production of traffic signal housings or road signs.
5. As translucent plastics containing glass fibers, optionally for light technology purposes (see for example DE-OS 1 554 020).
6. For the production of precision injection molded parts.
7. Optical applications, such as optical storage media (CD, DVD, MD), protective goggles or lenses for photographic cameras and film cameras (see for example DE-OS 2 701 173).
8. For socket housings as well as plug-type connectors.
9. As support material for organic photoconductors.
10. For the production of lights, e.g. vehicle headlamps, diffuse lighting panels or lamp covers.
11. For medical applications, e.g. oxygenators, dialysers.
12. For foodstuffs applications.
13. For uses in the automobile sector.
14. For sports articles.
15. For household articles, such as for example sink units and letterbox housings.
16. For housings, such as e.g. electrical distribution panels, electrical appliances, domestic appliances.
17. Construction parts of household articles, electrical appliances and electronic equipment.
18. For the production of motorcycle helmets and protective helmets.
19. For miscellaneous applications, such as e.g. stall-feeding doors or animal cages.
The polyester carbonates according to the invention are most particularly suitable for the production of optical and magnetooptical articles, in particular data storage media such as CD, DVD, MD and their derivatives, i.e. writeable and rewriteable data carriers, e.g. CD-ROM, CD-R, CD-RW, DVD-ROM, HD-DVD, etc.